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SubjectQuestion about usage of RCU in the input layer
Hi,

the input layer does a "synchronize_rcu()" after a list_add_tail_rcu(), which
is costing me 1 second of boot time.....
And based on my understanding of the RCU concept, you only need to synchronize on delete,
not on addition... so I think the synchronize is entirely redundant here...

Can I have my second of boot time back please ?



diff --git a/drivers/input/input.c b/drivers/input/input.c
index 1730d73..d69ec56 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1544,7 +1544,6 @@ int input_register_handle(struct input_handle *handle)
return error;
list_add_tail_rcu(&handle->d_node, &dev->h_list);
mutex_unlock(&dev->mutex);
- synchronize_rcu();

/*
* Since we are supposed to be called from ->connect()
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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